Stereophonic reproducing systems employing two spaced apart loudspeakers, one reproducing the so-called "left-hand" sound and the other reproducing the so-called "right-hand" sound, are known to provide a perfect stereophonic impression on the auditor only if this auditor is positioned on the medium perpendicular of the line interconnecting the two loudspeakers.
When the auditor moves away from this perpendicular, the stereo effect experienced by him will become less and eventually, at a sufficient distance from the perpendicular, the stereo effect will have essentially changed into a mono effect. This means that when the auditor moves away from the perpendicular in the left-hand direction, he will only hear the sound reproduced by the left-hand loudspeaker and, when listening to a performing group, he will hence obtain the impression that he is positioned entirely on the left-hand side of this group. Self-evidently, a similar situation presents itself when moving away from the medium perpendicular in the right-hand direction.